The present invention relates to a novel Quonset-type (semicircular arching roof type) pipe-frame greenhouse for horticulture, i.e. cultivation of fruits, flowers, vegetables and the like plants.
There is known a Quonset-type greenhouse in the prior art constructed with a plurality of pipe-frame rib members of each a semicircular or inverted U-shaped form erected upright on the ground in parallel with each other and connected together with at least one longitudinal connecting member to form a skeletal framework and provided with walls made, in place of traditional glass panes, of a transparent or translucent plastic film or sheet to admit entrance of sunlight on to the plants under growing.
The advantage obtained with such a sheet-walled pipe-frame Quonset-type greenhouse is that, in addition to the relative simpleness in the structure and hence low costs for construction in comparison with traditional glass-paned greenhouses, a convenient way is provided for the ventilation between inside and outside of the greenhouse at least in the vicinity of the ground by merely turning up or rolling up the lower end portion of the sheet wall in order to promote healthy growth of the plants under cultivation.
The problem in the greenhouses of the above described type is that, while sufficient ventilation can be obtained when the growing plants are still small, i.e. when the ventilation in the vicinity of the ground is essential or sufficient, no satisfactory ventilation is obtained in the upper portion of the greenhouse so that healthy growth of the plants is greatly disturbed when the plants have grown to have tallness approximating the roof of the greenhouse and the plants may sometimes become rotten or moldered in the top portions thereof.
As a remedy for the above problem, there has been proposed a greenhouse having a top opening capable of being opened and closed according to need. Such a greenhouse provided with a top opening is, however, not quite satisfactory because the top opening must be closed in a stormy weather or in a heavy rain in order to keep the atmosphere in the greenhouse not overly humid.